NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Feb 26, 4:09 PM EST, 4 hours 51 minutes earlier.
Area forecast discussion, Feb 26, 4:09 PM EST, 4 hours 51 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
409 PM EST TUE FEB 26 2013
.SYNOPSIS...
LOW PRESSURE IN SOUTHERN INDIANA WILL MOVE NORTHEAST TOWARD THE
SOUTHERN GREAT LAKES TONIGHT. A SECONDARY LOW WILL DEVELOP TONIGHT
OVER THE NORTHERN MID ATLANTIC REGION. THE TWO EVENTUALLY WILL
CONSOLIDATE INTO A SLOW-MOVING SYSTEM THAT WILL BEGIN TO SHIFT
EAST AND AWAY FROM OUR AREA ON THURSDAY. A HIGH PRESSURE RIDGE TO
THE WEST WILL MAKE VERY SLOW PROGRESS EASTWARD IN THE WAKE OF THE
LOW. ANOTHER LOW PRESSURE SYSTEM MAY FORM OFF THE SOUTHEAST COAST
SUNDAY, THE LOW PRESSURE SYSTEM WILL MOVE AWAY FROM REGION MONDAY
WITH HIGH PRESSURE OVER THE REGION ON TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
A RATHER COMPLEX MIXED PRECIPITATION TYPE EVENT IS IN STORE FOR OUR
NORTHWEST ZONES, WHILE THE REMAINDER OF OUR FORECAST AREA WILL SEE
MOSTLY MODERATE RAIN AS A LOW PRESSURE SYSTEM PROGRESSES INTO THE
SOUTHERN GREAT LAKES TONIGHT AND A SECONDARY LOW FORMS OVER THE
NORTHERN MID ATLANTIC AND PASSES OVER OUR AREA. LIGHT TO MODERATE
RAIN WILL BEGIN TO OVERSPREAD THE AREA FROM SOUTHWEST TO NORTHEAST
BY EARLY THIS EVENING. FOR OUR NORTHWEST ZONES, HOWEVER,
TEMPERATURES AT THE SURFACE AND ALOFT THIS EVENING WILL LIKELY
SUPPORT A MIXTURE OF RAIN/SNOW OR SLEET AT THE ONSET. NIGHTTIME LOW
TEMPERATURES WILL LIKELY OCCUR DURING THE FIRST HALF OF THE NIGHT,
WITH TEMPS SLOWLY RISING THEN TOWARD DAYBREAK. TODAY'S MODEL
GUIDANCE INDICATES THAT SURFACE TEMPERATURES WILL REMAIN COLD ENOUGH
TO ALLOW FOR AN EXTENDED PERIOD OF WINTRY PRECIPITATION OVER THE
SOUTHERN POCONOS. A COMBINATION OF SLEET, SNOW, AND FREEZING RAIN IS
EXPECTED WITH A FEW TENTHS ICE ACCRETION AND A FEW INCHES SNOW
ACCUMULATION. TERRAIN ELEVATION WILL LIKELY PLAY A ROLE IN
DETERMINING WHERE FREEZING RAIN LASTS LONGER VERSUS THE COLUMN BEING
COLD ENOUGH FOR SNOW. WITH THE EXPECTED QPF AND ACCUMULATION AMOUNTS
OF WINTRY PRECIPITATION, A WINTER STORM WARNING IS IN PLACE FOR
CARBON AND MONROE COUNTIES WITH A WINTER WEATHER ADVISORY FOR SUSSEX
COUNTY, NJ. ISOLATED POWER OUTAGES ARE POSSIBLE IF ICING OCCURS ON
TREES AND POWER LINES.
ELSEWHERE ACROSS THE FORECAST AREA, MODERATE TO PERHAPS BRIEFLY
HEAVY RAIN WILL OCCUR THROUGH THE OVERNIGHT HOURS, GRADUALLY
TAPERING OFF AROUND DAYBREAK WEDNESDAY. MOST LOCATIONS WILL SEE
AROUND ONE INCH OF LIQUID PRECIPITATION, AND THIS MAY CAUSE A FEW
AREAS OF POOR DRAINAGE FLOODING AND PERHAPS A FEW SMALLER
STREAMS/CREEKS TO APPROACH BANKFULL. HOWEVER, WE DO NOT EXPECT ANY
WIDESPREAD FLOODING PROBLEMS. WINDS WILL GENERALLY BE OUT OF AN
EASTERLY DIRECTION, WITH GUSTS AROUND 30 TO 35 MPH, STRONGEST NEAR
THE NJ COAST.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
GOING THROUGH WEDNESDAY, THE AREA OF LOW PRESSURE AROUND THE GREAT
LAKES AND THE SECONDARY LOW OVER THE MID ATLANTIC STATES WILL
GRADUALLY CONSOLIDATE INTO A BROAD, SLOW-MOVING SYSTEM THAT WILL
BEGIN TO SHIFT TO OUR NORTH AND EAST. AREAS OF LIGHT RAIN WILL
GRADUALLY TAPER OFF FROM SOUTH TO NORTH ACROSS OUR REGION, HOWEVER
THE CHANCE FOR RAIN WILL LINGER INTO THE AFTERNOON FOR THE NORTHERN
THIRD OF OUR REGION. BY THE EARLY EVENING, PRECIPITATION MAY BE A
RAIN/SNOW MIX OVER THE SOUTHERN POCONOS. OVERALL, LIGHTER QPF
AMOUNTS ARE EXPECTED DURING THE DAY, WITH MOST AREAS SEEING A FEW
TENTHS OF AN INCH.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
A GFS AND WRF-NMMB BLEND SEEMED TO INITIALIZE THE BEST OFF THE 12Z
SOUNDINGS. THE MODELS IF ANYTHING WERE ABOUT 1C TOO COLD AT 850MB
AND 925MB WITH THEIR INITIALIZATION AT UPSTREAM POINTS. THE GENERAL
MODEL TREND WAS SLIGHTLY SLOWER, BUT SLIGHTLY FARTHER NORTH WITH THE
CLOSED LOW THAT IS ASSOCIATED WITH OUR NEAR AND SHORT TERM WEATHER.
AS SUCH AT THE START OF THE LONG TERM, IT WILL TAKE A WHILE FOR PCPN
CHANCES TO CEASE IN OUR FORECAST. A BIT OF A BREAK ON WEDNESDAY
SHOULD BE REPLACED BY DEEPER MOISTURE AND MORE SHORT WAVES ON
WEDNESDAY NIGHT. GIVEN THE WARM PROJECTIONS, THE MODELS (WRF IN
PARTICULAR) HAVE BACKED AWAY FROM THE SOUTHERN EXTENSION OF SNOW FOR
WEDNESDAY NIGHT. TOUGH AT THIS POINT WITH MULTIPLE SHORT WAVE
SOLUTIONS TO LEAVE ANY PART OF OUR CWA DRY WITH THE OVERALL BEST
CHANCES NORTH. SNOW CHANCES AND QPF ARE NOT COINCIDING AND SNOWFALL
IN THE GRIDS AT THIS JUNCTURE NORTHWEST QUARTER OF OUR CWA WERE KEPT
MODEST.
WHILE IT WILL BE GETTING COLDER ALOFT ON THURSDAY, THE AIR MASS
BELOW IT WILL CONTINUE TO MODIFY AT A LESSER RATE. WHILE THIS WILL
MAKE IT MORE UNSTABLE PER SE, WE WILL REMAIN THERMALLY CHALLENGED
IN MOST OF OUR CWA TO HAVE PCPN FALL AS SNOW AS LONG AS THE
INTENSITY IS ON THE LIGHTER SIDE. THUS THE FCST/GRIDS DID BUY INTO
AN INCREASING LARGER AREA OF OUR CWA WITH RAIN AS A PTYPE ON
THURSDAY EXCEPT FAR NORTHWEST. POPS ARE FOLLOWING A SIMILAR
SCENARIO AS WEDNESDAY NIGHT WITH THE HIGHEST POPS NORTH CLOSEST TO
THE CLOSED LOW. INSTABILITY RELATIVELY SPEAKING DOES PEAK TOWARD
EVE IN NJ AND DE AND IF THIS REMAINS SO, WE MIGHT BE ABLE TO SHOW
A MORE DIURNALLY DRIVEN AFTN PEAK THERE IN FCSTS AHEAD. BASED ON
FCST 925MB AND 850MB TEMPS (UNLESS THEY ARE TOO LOW), GFS MOS
LOOKS TOO WARM FOR MAX TEMPS AND THEY WERE KEPT CLOSER TO
CONTINUITY AND NAM MOS.
WITH THE CLOSED LOW EXITING TO THE EAST ON THURSDAY NIGHT, WE KEPT
JUST LOW POPS EARLY AND MAINLY CONFINED TO THE FAR EASTERN AND
NORTHERN PARTS OF OUR CWA. ON FRIDAY DAY MENTION OF FLURRIES WAS
CONFINED TO THE POCONOS. FLOW OFF THE LAKE NOT IDEAL, BUT THERE ARE
MODEL HINTS OF SFC TROFFING LINGERING NORTH OF OUR CWA. THERE IS A
FORECAST INVERSION WORKING ITS WAY DOWNWARD, WHICH MAY BECOME A
CAPPING FACTOR AND MAKE THIS A MUTE POINT. ELSEWHERE THERE SHOULD
BE LESS SELF DESTRUCT SUNSHINE THAN THERE WILL BE ON THURSDAY. MAX
TEMPS FRIDAY ARE CLOSER TO HPC GUIDANCE AND EC MOS AS GFS MOS
STILL APPEARS TOO WARM.
ON THE WEEKEND AS THE NEXT TROF DIGS INTO THE EASTERN CONUS. ALL
OF THE MODELS HAVE CYCLOGENESIS FAR ENOUGH OFFSHORE TO NOT BE A
FACTOR ON LAND (MAYBE SWELLS FOR OCEAN WATERS). FWIW THE GEFS AND
EURO ENSEMBLE MEANS ARE NOT INFERRING TOO MANY WEST OF THE OP
MODEL MEMBERS. THE FORECAST WILL BE KEPT DRY. COLDER ALOFT, SO WE
KEPT THE DOWNWARD TRENDING OF TEMPERATURES CONTINUING.
LOW PRESSURE OFF THE EAST COAST SHOULD CONTINUE MOVING OUT TO SEA
WITH HIGH PRESSURE BUILDING BACK IN MONDAY AND TUESDAY. CLOUDS
SHOULD GRADUALLY CLEAR OUT MONDAY AND GIVE WAY TO MORE SUNSHINE BY
TUESDAY WITH HIGH PRESSURE OVER THE REGION. GOOD MODEL AGREEMENT ON THE
OVERALL SCENARIO FOR MONDAY AND TUESDAY. WENT A TOUCH UNDER MOS AND
HPC GUIDANCE ON TEMPERATURES AND A TOUCH OVER FOR WINDS ON MONDAY.
THIS IS DUE TO THE STRONG CAA BETWEEN A HIGH PRESSURE SYSTEM
ADVANCING IN AND LOW PRESSURE MOVING AWAY. FELT SPLITTING THE
DIFFERENCE WAS THE BEST APPROACH BETWEEN THE WARM MEX GUIDANCE AND
THE COOL RAW GUIDANCE FOR HIGHS TUESDAY. ALL OTHER ELEMENTS WERE
KEPT CLOSE TO HPC GUIDANCE WITH GOOD MODEL AGREEMENT OVERALL ON
TUESDAY. EARLIER MODEL RUNS HAD BEEN BRINGING IN THE NEXT SYSTEM AT
THE END OF THIS FORECAST PERIOD. HOWEVER, WILL HOLD OFF ON ANY
PRECIPITATION CHANCES TILL TUESDAY NIGHT AS THE 12Z RUNS HAVE SLOWED
THE ARRIVAL OF THIS SYSTEM. THOUGH, SOME GFS ENSEMBLE MEMBERS HAVE A
FASTER ARRIVAL OF THIS SYSTEM. THE MOST LIKELY TRACK OF THIS SYSTEM
ATTM IS TO OUR SOUTH WITH IT BEING A MORE WINTRY TYPE SYSTEM
GIVEN THE POTENTIAL FOR BLOCKING AND THE EXPECTED TELECONNECTION
STATES.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
CONDITIONS WILL BE DETERIORATING TO MVFR THIS EVENING AND EVENTUALLY
IFR TONIGHT FOR ALL TERMINAL AS LIGHT TO MODERATE RAIN OVERSPREADS
THE REGION FROM SOUTHWEST TO NORTHEAST. EASTERLY WINDS WILL ALSO BE
INCREASING THIS EVENING AND TONIGHT, WITH GUSTS IN THE 25 TO 30 KNOT
RANGE EXPECTED. CONDITIONS ARE EXPECTED TO REMAIN AT IFR BEYOND
DAYBREAK WEDNESDAY WITH SOME LIGHT RAIN. BY MID TO LATE WEDNESDAY
MORNING, GRADUAL IMPROVEMENT TO MVFR IS EXPECTED. WINDS WILL
GRADUALLY BECOME MORE SOUTHWESTERLY DURING THE COURSE OF THE DAY,
AND IMPROVEMENT TO VFR IS EXPECTED DURING THE AFTERNOON.
OUTLOOK...
WEDNESDAY NIGHT AND THURSDAY...WHILE AVERAGING VFR, SOME MAINLY MVFR
CONDITIONS ARE POSSIBLE IN SHOWERS. ANY CHANCE OF SNOW SHOWERS SEEMS
CONFINED TO THE NORTHWESTERN SITES. CONFIDENCE IS LOW TO
MODERATE.
THURSDAY NIGHT THROUGH SUNDAY...MAINLY VFR. WEST TO NORTHWEST WINDS
OVERALL ARE NOT EXPECTED TO DEVIATE MUCH FROM CLIMATOLOGICAL
AVERAGES FOR THIS TIME OF YEAR. CONFIDENCE IS LOW TO MODERATE.
&&
.MARINE...
A GALE WARNING FOR OUR COASTAL WATERS AND DELAWARE BAY WILL LAST
THROUGH THE OVERNIGHT HOURS. EASTERLY WIND GUSTS IN THE 35 TO 40
KNOT RANGE ARE EXPECTED, WITH SEAS RANGING FROM 6 TO 11 FEET FOR
THE COASTAL WATERS AND 2 TO 4 FEET IN DELAWARE BAY. AREAS OF
MODERATE RAIN ARE EXPECTED WHICH WILL REDUCE VISIBILITIES. WINDS
AND SEAS WILL BE DIMINISHING GOING THROUGH WEDNESDAY AS LOW
PRESSURE GRADUALLY MOVES NORTH OF THE REGION.
OUTLOOK...
THERE SHOULD BE RESIDUAL SMALL CRAFT ADVISORY CONDITIONS ON THE
OCEAN THROUGH WEDNESDAY NIGHT DUE TO THE SEAS WITH SUB-ADVISORY
CONDITIONS EXPECTED ON DELAWARE BAY.
CONDITIONS OVER THE OCEAN WATERS AND DELAWARE BAY (LOWER IN
PARTICULAR) MAY OSCILLATE AROUND THE ADVISORY CRITERIA THROUGH
THE REST OF THE WORK WEEK AS THE SYSTEM MOVES AWAY SLOWLY.
ULTIMATELY, SUB-ADVISORY CONDITIONS ARE EXPECTED OVER THE
WEEKEND THROUGHOUT. THE ONE CAVEAT LATE IN THE WEEKEND SWELLS AND
AN INCREASE NORTHWEST FLOW IN THE WAKE OF THE DEVELOPING OFFSHORE
LOW MIGHT BRING SMALL CRAFT ADVISORY CONDITIONS BACK. HIGHER
CHANCES OVER THE OCEAN THAN THE DELAWARE BAY AT THIS JUNCTURE.
&&
.HYDROLOGY...
PRECIPITATION TOTALS OF AROUND AN INCH ARE EXPECTED WITH THE NEXT
SYSTEM. THE GREATEST TOTALS WILL BE FOUND ACROSS THE NRN AREAS OF
NJ AS THE SYSTEM CONTINUES TO ORGANIZE WHILE MOVING ACROSS THE
AREA. THESE TOTALS LOOK A BIT SHORT (COMPARED WITH FLOOD GUIDANCE)
TO CAUSE ANY WIDESPREAD FLOODING PROBLEMS. WE WILL REFRAIN FROM
ISSUING ANY HYDRO RELATED FLAGS.
&&
.TIDES/COASTAL FLOODING...
A DECENT ONSHORE FLOW WILL SET UP TODAY AND CONTINUE TONIGHT. HIGHER
SURGE VALUES ARE EXPECTED WITH THE UPCOMING FEW TIDE CYCLES. THE
HIGH TIDES TONIGHT AND WED MORNING (OCEAN AND DELAWARE BAY - A BIT
LATER OVER CHESAPEAKE BAY) LOOK TO BE THE ONES WITH THE MOST
POTENTIAL FOR ANY TYPE OF TIDAL FLOODING. THE NUMBERS AT THIS TIME
APPEAR TO FALL IN THE LOW END OF THE MINOR TIDAL FLOODING RANGE.
THE MOST LIKELY SCENARIO FOR CHESAPEAKE BAY IS SPOTTY MINOR TIDAL
FLOODING, AND NO STATEMENT WILL BE ISSUED AT THIS TIME. ELSEWHERE,
FOR THE NJ/DE COASTS AND INTO DELAWARE BAY AND THE TIDAL DELAWARE,
A COASTAL FLOOD ADVISORY IS IN PLACE AS WE EXPECT TO REACH LOW END
MINOR TIDAL FLOODING.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...COASTAL FLOOD ADVISORY FROM 10 PM THIS EVENING TO 5 AM EST
WEDNESDAY FOR PAZ070-071.
WINTER STORM WARNING UNTIL 9 AM EST WEDNESDAY FOR PAZ054-055.
NJ...COASTAL FLOOD ADVISORY UNTIL 10 AM EST WEDNESDAY FOR
NJZ012>014-020-026.
COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
NJZ021>025-027.
COASTAL FLOOD ADVISORY FROM 10 PM THIS EVENING TO 5 AM EST
WEDNESDAY FOR NJZ016>019.
WINTER WEATHER ADVISORY UNTIL 9 AM EST WEDNESDAY FOR NJZ001.
DE...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
DEZ002>004.
COASTAL FLOOD ADVISORY FROM 10 PM THIS EVENING TO 5 AM EST
WEDNESDAY FOR DEZ001.
MD...NONE.
MARINE...GALE WARNING UNTIL 5 AM EST WEDNESDAY FOR ANZ450>455.
GALE WARNING UNTIL 3 AM EST WEDNESDAY FOR ANZ430-431.
&&
SYNOPSIS...DELISI/GIGI/GAINES
NEAR TERM...KLINE
SHORT TERM...KLINE
LONG TERM...GAINES/GIGI
AVIATION...DELISI/GIGI/KLINE
MARINE...DELISI/GIGI/KLINE
HYDROLOGY...
TIDES/COASTAL FLOODING...